The invention relates to a composition of matter, a method of preparing same, catalyst, a method of producing the catalyst and a process of using the catalyst. In another aspect, the invention relates to a particularly effective ethylene polymerization catalyst and process.
In the production of polyolefins, such as, for example, polyethylene, polypropylene, ethylene-butene copolymers etc., an important aspect of the various processes and catalysts used to produce such polymers is the productivity. By productivity is meant the amount or yield of solid polymer that is obtained by employing a given quantity of catalyst. If the productivity is high enough then the amount of catalyst residues contained in the polymer is low enough that the presence of the catalyst residues does not significantly affect the properties of the polymer and the polymer does not require additional processing to remove the catalyst residues. As those skilled in the art are aware, removal of catalyst residues from polymer is an expensive process and it is very desirable to employ a catalyst which provides sufficient productivity so that catalyst residue removal is not necessary.
In addition, high productivities are desirable in order to minimize catalyst costs. Therefore it is desirable to develop new and improved catalysts and polymerization processes which provide improved polymer productivities.
Many of the prior art catalysts create serious problems in the particle-form polymerization processes because the particle size of the polymeric product is so fine that difficulties are encountered in the separation and handling of the product; particularly, trouble occurs in the extrusion and compounding steps involved in producing a commercial product. A method has been found now to keep the high activities of certain of these new generation ethylene polymerization catalysts and yet produce polymer of sufficiently large size so that the above-referred to problem is reduced or eliminated completely.
Accordingly, an object of the invention is to provide a catalyst.
Another object of the invention is to provide a polymerization process for using a catalyst capable of providing improved polymer productivities as compared to prior art catalysts.
Another object of the invention is to provide a catalyst and a polymerization process which produces attrition resistant relatively large as formed polymer particles.
Other objects, aspects, and the several advantages of this invention will become apparent to one skilled in the art upon reading this disclosure and the appended claims.